The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
Wireless networks providing voice and data services are constantly expanding capacity to keep up with demand. Infrastructure build-out has traditionally comprised of adding more base stations and accompanying hardware at existing sites and adding new sites. State of the art antenna solutions are based on directional antennas utilizing radiating elements and a reflector. For applications where there are high data traffic requirements, multi-beam antenna solutions are becoming increasingly important. Multi-beam antennas are able to cover a wide area of coverage depending on the requirement and the antenna design (up to 360 degrees) while providing multiple beams for a given frequency or frequency range. Aside from traditional phased-array solutions, which have key drawbacks such as scope of coverage (can provided limited coverage, i.e., not 360 degrees), size and individual beam performance (degradation of gain on side beams), there are possibilities of using a RF lens approach.
One proposed solution is using cylindrical RF Lenses which are capable of providing multiple beams for different sector coverage. However, using a cylindrical lens approach can present challenges for providing 360 degree coverage as when feeds (emitters) are traditionally positioned around the circumference of the cylinder, there is interference from opposing feeds (feeds placed directly opposite each other on the cylinders circumference).
Furthermore this approach is limited in providing a narrow vertical beam. Due to the shape of the cylinder, only the horizontal resultant beam-width of the feed is affected by the cylinder while the vertical beam-width remains unchanged. Another approach is to use a spherical lens such as a Luneburg Lens, which, due to its symmetrical spherical shape equally narrows both the resultant horizontal and vertical beam-width of the feeds placed around the circumference of the Lens. However even though this approach provides reduced interference from opposing feeds (based on the size of the sphere used, the resultant beam would be several times larger than the opposing feed, thus reducing its interference), interference still exist and the size and cost of the solution provide drawbacks to this approach. Aside from the feeds themselves, the required cable lines and any support structures further add to interference for both lens approaches. Therefore the challenge is providing a 360 multi-beam solution with limited interference from feeds, cable lines and any support structures.
Thus, there is still a need for an effective and efficient antenna for use with extremely high capacity wireless communication systems.
All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.